Samsung CEC return key 0x91 mapping fix

Samsung uses non-standard CEC code for "return" key. 

Code 0x91 - CEC_USER_CONTROL_CODE_AN_RETURN   is currently wrongly  mapped to ContextMenu.

This is picture of Samsung remote. (see key labelled as "return" )
http://cnet3.cbsistatic.com/hub/i/r/2014/04/18/87d5c07d-f256-4afd-908e-d13534a3e9ee/resize/770x578/d01f7a66d77a53060a46b8dc8a5f7c5d/samsung-un55h6400-product-photos03.jpg

Mapping it to context menu is clearly wrong.

This request fixes this mapping.